It is well known in the art of induction cooking appliances that inductors, i.e. induction coils, present a strong part to part variation especially in a not entirely automatic process of manufacturing these components (i.e. a process entirely carried out by robots or the like), particularly when the coil pancake elements are joined together using a glue which is also used to fix not only inductor and ferrites, but also mineral wool, mica and aluminum tray.
This aspect significantly influences the cooktop performances and the design development, and therefore the production process strongly affects the inductor quality. For the above reasons many appliance producers now use a plastic frame structure that increases the uniformity of products because it fixes the routing of the coil winding turns and the relative position between ferrites and wire.
A great number of producers adopt a solution in which induction coils are mounted on a plastic frame which is used for the coil winding on one side and for placing the ferrite bars on the other side. There are also solutions with a plastic frame is used only for ferrite bars while the winding is placed over with glue or bi-adhesive stripes.
The above known solutions have the disadvantage of making the production process quite complex and difficult to carry out in a totally automatic way. Moreover, the different temperatures reached by the magnetic field concentration bars and coil lead the designer to choose a polymeric material which can withstand the highest temperatures and therefore the polymeric support needs to be made of a quite expensive polymer which can withstand such high temperatures.
The technical solution of the induction cooking heater disclosed by CN201414236 has the disadvantage of increasing the distance between the windings of the inductor and the ceramic glass where a cooking utensil is placed. This is due to the thickness of the first plastic frame which is interposed between the windings and the glass of the cooking appliance. Such an increased distance decreases the energy efficiency of the inductor. Moreover, since the windings of the inductor on the first plastic frame is usually performed so that the wire is placed on the frame from above, it is necessary to flip over the upper frame during the assembly process of the two frames, and this leads to a complication of the assembly line.
Another disadvantage of the above known solution derives from the almost identical diameters of the two plastic elements which are connected on their peripheral edge, since this requires a large amount of polymeric material.
It is an object of the present disclosure to provide an induction cooking heater which does not present the problems detailed above.